Lithium base alloy



n ed States Patent 3,041,164 Patented June 26, 1962 This invention relates to a jet propulsion fuel and in particular to an alloy hydro-fuel composition.

The object of the present invention is to provide a hydrotuel which is spontaneously ignitable in water, has a high specific gravity and a high energy content per unit weight and per unit volume.

A further object of this invention is to produce a hydrofuel which has a low and sharp melting point and low viscosity, which is low in cost and which maybe handled with ease and with safety.

Numerous attempts have been made heretofore to produce hydrofuels with properties which will permit their use in underwater propulsion devices. For example, previous experimenters have compounded alloys of lithium, aluminum and sodium melting over a range of from about 348 F. to about 450 F. The melting point of such an alloy is within the range of potential use as a hydrofnel; however, the excessive viscosity of the alloy, even when melted, all but prevents its use for such purposes due to the difficulties of pumping and transmitting the hydrofuel into the combustion region.

I have discovered an improved hydrofuel having a lithium base which possesses a relatively low melting point but which has a high energy density due to the inclusion of substantial quantities of aluminum and which is nonetheless extremely low in viscosity. My novel hydrofuel is a calcium, lithium, aluminum, sodium alloy.

I have found that the desired properties of low melting, high energy density, low viscosity and water ignition are obtained when calcium, lithium, aluminum and sodium are alloyed within the ranges of proportions set forth below:

To better illustrate my invention I have set forth in Table I below the proportions and properties of a series of alloys prepared according to my invention. In the first four lines of the table are set forth the properties of lithium, aluminum, sodium and calcium, the constituents of my new alloys, for comparative purposes. Alloys A Table I Alloy No. Li 1 Al 1 Na 1 Ca 1 Percent by weight. 2 Degrees Fahrenheit.

through D are representative of alloys compounded using the same constituent elements but in proportions falling outside those necessary in the practice of my invention.

Those skilled in the art will readily appreciate that virtually an infinite number of alloys can be compounded using the above metals in varying proportions within the ranges specified.

Examples of other alloys within the scope of my invention are the following:

Table II (Percent by Weight) Ll Al Na Ca The preferred composition of my invention is alloy 5 in Table I. This alloy melts sharply at 343 F. and is completely fluid at its melting point. It is spontaneously ignitable with water, as are all of the alloys of my invention, and possesses an extremely high energy density. In comparison with pure lithium, alloy 5 has an energy density 20% better on a weight basis and better on a volume basis.

The alloys of my invention are compounded by melting the component metals in the desired proportions under an inert atmosphere with accompanying stirring to insure complete dispersion. After complete mixing has occurred, the alloy is cast in molds of appropriate shape and permitted to cool. The solid ingots are then stored under airtight anhydrous conditions. The ingots may be stored until needed in either water-proof airtight containers or under nonreactive organic liquids such as white mineral oil.

The novel hydrofuel alloys of my invention can be used as aprimary source of fuel in underwater propulsion systems such as that described in assignees copending US. Patent Application S.-N. 27,574, filed May 17, 1948, by Calvin A. Gongwer, for Jet :Propulsion Device for Operation Submerged in Water.

Since modifications and variations may obviously be made in the hydrofuel of the present invention, it is intended that the examples given above shall be interpreted as being merely illustrative and not imposing any limitations upon the invention.

I claim:

1. A low melting, high energy content hydrofuel alloy consisting essentially of from about 50% to about by weight lithium; from about 30% to about 2% by Weight aluminum; from about 15% to about 3% by Weight sodium; and from about 5% to about 40% by weight calcium.

2. A low melting, high energy hydrofuel alloy consistingessentially of about 66.4% lithium, 16.6% aluminum, 7.0% sodium and 10.0% calcium by weight.

3. A low melting, high energy hydrofuel alloy consisting essentialy of about 51% lithium, 10% aluminum, 5% sodium and 34% calcium by weight.

4. A low melting, high energy hydrofuel alloy consisting essentially of about 55% lithium, 2.5% aluminum, 5% sodium and 37% calcium by weight.

5. A low melting, high energy 'hydrotuel alloy consisting essentialy of about 54% lithium, 5% aluminum, 5% sodium and 36% calcium by weight.

6. A low melting, high energy hydrofuel alloy consisting essentially of about 52.5% lithium, 7.5% aluminum, 5% sodium and 35% calcium by weight.

7. A low melting, high energy hydrotuel alloy consisting essentially of about 55.4% lithium, 27.6% aluminum, 7% sodium and 10% calcium by weight.

3 8. A low melting, high energy hydrofuel alloy consist- Applications, The Electrochemical Society, Inc., New ing essentially of about 58.1% lithium, 24.9% aluminum, York 1935. 7% sodium and 10% calcium by weight. Mantell aud Hardy: Calcium, Metallurgy and Tech- References Cited in the file of this patent nology Remhold Pubhshmg Corp" New York 1945 5 Pages 129-131. Osborg: L1thium, Theoretical Studies and Practical valdmani: Metallurgy (Russ.) 12, No. 8, 85 (1937). 

1. A LOW MELTING, HIGH ENERGY CONTENT HYDROFUEL ALLOY CONSISTING ESSENTIALLY OF FROM ABOUT 50% TO ABOUT 75% BY WEIGHT LITHIUM; FROM ABOUT 30% TO ABOUT 2% BY WEIGHT ALUMINUM; FROM ABOUT 15% TO ABOUT 3% BY WEIGHT SODIUM; AND FROM ABOUT 5% TO ABOUT 40% BY WEIGHT CALCIUM. 